This invention relates to a mine roof support assembly constituted by three mine roof support units positioned side-by-side along a beam.
A known form of assembly of this type has the central unit fastened to the beam for movement therewith and the two outer units connected to the beam by means of respective guide rod assemblies. Where the floor of the mine working is uneven, or where there is a relatively steep incline or dip in the floor level, problems arise in ensuring satisfactory alignment of the units and the beam. This is particularly troublesome when the assembly is used as a support for a longwall face.
DT-OS 2,337,218 described a mine roof support assembly of this type in which the central unit forms an abutment for the advance of the two outer units. The guide rod assemblies of the outer units are constituted by resilient guide rods connected to the beam, and the advance rams of the outer units are also connected to the beam. In order to align this assembly, an aligning ram is positioned between the central unit and the outer unit which lies below it down the incline, the purpose of this alignment ram being to align the central unit relative to the beam and thus also relative to the two outer units. However, it is not always possible with this assembly to align the beam itself.
DT-OS 1,583,091 describes an assembly having three mine roof support units, the two outer units being connected by alignment rams which are positioned between these two units in the manner of guide bars. A separate alignment device, associated with these rams, is provided for aligning the central unit. This type of arrangement is not suitable, however, for the type of assembly having a beam fastened to the central unit.
DT-OS 2,453,225 describes a longwall face mine roof support assembly constituted by three units. Here, the central unit carries a generally U-shaped guide bar, the two parallel arms of which form guide rods for the two outer units. The U-shaped guide bar is longitudinally adjustable by means of an alignment ram so that the spacing of the units can be varied. Again this type of arrangement is not suitable for the type of mine roof support assembly which has a beam fastened to its central unit.
It is the main object of the invention to construct a mine roof support assembly of the type defined above which permits all the units and the beam to be aligned even where the floor level of the mine working dips appreciably and without the adaptability of the individual units to any uneveness of the floor being affected.